Brownish ape is on the move (5)
I believe the answer is:
sepia
'brownish' is the definition.
(I've seen this before)
'ape is on the move' is the wordplay.
'on the move' is an anagram indicator.
'ape'+'is'='apeis'
'apeis' is an anagram of 'SEPIA'.
(Other definitions for sepia that I've seen before include "Brownish tone associated with old photographs" , "Dark reddish-brown pigment" , "Sort of drawing" , "Denizen of deep" , "Brown colour of old photo" .)